NEUTRON-IRRADIATION EFFECTS ON THERMAL-SHOCK RESISTANCES AND FRACTURE-MECHANICAL PROPERTIES OF FUEL COMPACTS FOR THE HTTR

To simulate the nuclear fuel for the High Temperature Engineering Test Reactor (HTTR), a fuel compact model using SiC-kernel coated particle s instead of UO2-kernel coated particles was prepared under the same c onditions as those for the real fuel compact. The mechanical and fract ure mechanics properties were studied at room temperature. The thermal shock resistance and fracture toughness for thermal stresses of the f uel compact model were experimentally assessed by means of are dischar ge heating applied at a central area of the disk specimens. These mode l specimens were then neutron irradiated in the Japan Material Testing Reactor (JMTR) for fluences up to 1.7 x 10(21)n/cm(2) (E>29fJ) at 900 degrees C +/- 50 degrees C. The effects of irradiation on a series of fracture mechanical properties were evaluated and compared with the c ases of graphite IG-110 used as the core materials in the HTTR.